10
System Model Given a set of BSs, users and candidate locations All users are associated with a BS BSs are powered by renewable energy BSs and users may have different power levels of charging and transmission In a WLAN, BS and its associated users use the same transmission power 9

11
System Model No inter-WLAN interference with orthogonal channels assigned to BSs for inter-WLAN communication BSs can only be placed at a given set of candidate locations BSs at different candidate locations have different charging capabilities 10